rc : nit
noise reduction, use all eight categories of transform for inter blocks
noise reduction, cleaned unused buffer space
denoise: further cleanups

x264 used buffer pointers so that they could swap between normal denoise and
"emergency denoise" when the QP became very high.  We do not have an emergency
denoise and thus we don't need these pointers at this time. This simplifies
initialization and update logic.
refactor: move motion reference pointers from TEncSearch to Slice

The actual storage for the MotionReference instances lives in the FrameEncoder,
to save memory, but we don't want the analysis code to be aware of the FE so
we give it a pointer to this array.  Having that pointer live in TEncSearch
forces us to update this pointer each time a worker thread starts a new job.

Having the pointer in Slice means we only have to set it once, when the slice
first starts to be encoded. And having this pointer next to the RPS data in the
slice header makes this more coherent.
param: log noise reduction use/strength